Apparatus for inverting and coating a workpiece

ABSTRACT

An apparatus for producing holes in a workpiece by means of a laser beam and for coating both sides of disc-shaped workpieces which incorporates two band members guided above one another at a spacing along a predetermined path. This spacing of the band members is smaller than the height of the workpieces. One of the band member has a smooth surface and the other an adhesive surface, and two coating locations are arranged such that one is before and the other behind the aforementioned predetermined path.

Steffen et a1.

3,742,907 July 3, 1973 APPARATUS FOR INVERTING AND COATING A WORKPIECEInventors: Jurg Steffen, Zurich; Arnold Hofer,

Muttenz, both of Switzerland Assignees: Watch Stones Co., Ltd., Berne;

Turlabor AG, Zurich, Switzerland Filed: June 17, 1971 Appl. No.: 154,037

Related [1.8. Application Data Division of Ser. No. 12,691, Feb. 19,1970, Pat. No. 3,656,988.

Foreign Application Priority Data [56] References Cited UNITED STATESPATENTS 3,467,063 9/1969 Brinkley et al. 1 18/324 3,356,207 12/1967Hensel 198/165 X 2,355,879 8/1944 MacFarlane et 211.... 198/165 X2,907,441 10/1959 Nafziger 198/165 X Primary Examiner-J. V. TruheAssistant ExaminerGeorge A. Montanye Attorney-Werner W. Kleeman [57]ABSTRACT An apparatus for producing holes in a workpiece by means of alaser beam and for coating both sides of disc-shaped workpieces whichincorporates two band Feb. 27, 1969 Switzerland 2951/67 members guidedabove one another at a Spacing along Feb. 27, 1969 Switzerland 2956/69 apredetermined path. This spacing of the band hers is smaller than theheight of the workpieces. One 118/314 118/319 118/324 of the band memberhas a smooth surface and the other 118/351 219/121 L an adhesivesurface, and two coating locations are arlltt. Cl. B056 5/00 ranged Suchthat one is before and the other behind the Field of Search 118/324;198/33 AD, aforementioned predetermined path 3 Claims, 1 Drawing FigurefiflATl/VS APPARATUS FOR INVERTING AND COATING A WORKPIECECROSS-REFERENCE TO RELATED CASE The instant application is a divisionalapplication of our commonly assigned, co-pending United Statesapplication, Ser. No. l2,69l, filed Feb. 19, 1970 now US. Pat. No.3,656,988, and entitled: METHOD FOR THE FABRICATION F HOLES IN AWORKPIECE BY MEANS OF LASER-BEAMS AND APPARATUS FOR THE PERFORMANCE OFTHE AFORESAID METHOD.

BACKGROUND OF THE INVENTION The present invention relates to an improvedapparatus for the fabrication of holes in a workpiece by means oflaser-beams.

Methods for the fabrication of holes by means of laser-beams are knownto the art. In these known techniques there could not, however, beprevented that the front side of the workpiece and with through passingholes also at the rear side or face about the bore or hole openings,that there was formed such a cratershaped protrusion of material ejectedby the laserbeam which is fused with the workpiece, which, above all, isthen undesirable if a great deal of value is placed upon a planar orflat configuration of the bored or apertured surface.

It has already been proposed to coat the surface of the workpiece whichis to be contacted by the laserbeams. Yet, these coatings are neitherdestined to nor suitable for preventing the drawback of crater formationby virtue of the ejected material. Hence, it was desired with theseknown coatings to either improve the absorption or to generate a vaporpressure in order to keep the formed hole free, in other words, in orderto prevent the subsequent closing of such hole or bore.

SUMMARY OF THE INVENTION Accordingly, it is a primary object of thepresent in vention to provide an improved apparatus for the fabricationof holes or bores in a workpiece by means of laser-beams whicheffectively overcome the aforemen tioned drawbacks of the'prior arttechniques.

Another more specific object of the present invention relates to animproved apparatus of the character described, by means of which themounds or rejected material brought about by the laser-beam can bereadily removed from the relevant workpiece surface.

Still a further object of the present invention relates to an improvedapparatus for the formation of holes or bores in a workpiece by means ofa laser-beam in an economical and efficient manner wherein the materialejected during the boring process, by virtue of the action of thelaser-beam, can be readily removed from the surface of the workpiecewithout a great deal of additional treatment or work.

Now, in order to implement these and still further objects of thepresent invention, which will become more readily apparent as thedescription proceeds, the apparatus of the invention and serving forcoating both sides of substantially disc-shaped workpieces is generallymanifested by the features that there are provided two band members orthe like which are guided in superimposed fashion aboveone another at aspacing along a predetermined path, this spacing being smaller than the'height of the workpiece. One of these band members possesses a smoothsurface and the other an adhesive surface, and two contact locations arearranged in such a fashion that one such contact location is arrangedbefore and the other such contact location behind the aforementionedpredetermined path.

BRIEF DESCRIPTION OF THE DRAWING The invention will be better understoodand objects other than those set forth above will become apparent whenconsideration is given to the following detailed description thereof.Such description makes reference to the annexed drawing wherein thesingle FIGURE shows a preferred embodiment of inventive apparatus.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT OF APPARATUS Describingnow more specifically the invention under consideration, it has beenfound that by coating the surface impinged by the laser-beam of aworkpiece which is to be throughbored, or with throughgoing orthroughpassing holes, additionally coating the rear side of theworkpiece, with an organic boring agent, which upon contact with theejected material which is thrown out in liquid state during the boringoperation, changes and in turn, forms a non-adhering intermediate layerupon the workpiece surface between the material parti cles which areremoved by the laser-beam. Consequently, the ejected material aftertermination of the boring or aperturing process can be readily removedfrom the relevant workpiece surface without difficulty.

Furthermore, it has been found that by virtue of this surface film thelaser light can penetrate without difficulty into the material andenable a machining (boring) of the workpiece in accordance with theintensity distribution of the laser radiation.

Above all, as the organic coating agent there come under considerationpolymers, such as:

a. copolymers of methylmethacrylate, butylacrylate and quaternaryN,N-dimethylaminoethylmethacrylate,

b. copolymers of methylmethacrylate, decylmethacrylate and quaternaryN,N-dimethylaminoethylmethacrylate,

c. polyblends of polyvinylalcohol-polyvinylacetate andpoly-N,N-dimethylaminoethylmethacrylate.

Low molecular weight substances, such as sugar, for instance raw sugar.

A quaternary ammonium compound, for instance trimethyldecylammoniumchloride.

Mixtures of polymers and low molecular weight substances, such as forinstance poly(vinylacetatevinylalcohol) and trimethyldecylammoniumchloride.

An exemplary composition of a coating agent suitable for the purposes ofthe invention could be as follows methanol 990 ml copolymers 10 ml(consisting of 50% solids) copolymers of 2 mols. methylmethacrylate 1mol. butylacrylate 1 mol. N,N-Dimethylaminoethylmethacrylate, whereinthe entire mixture afterpolymerization is quaternized withbutyrolactone.

These substances are particularly suitable in dissolved condition forcoating of workpieces. However, the possibility also exists, at leastfor certain of these substances, to apply them in a paste-like conditionor also liquid or with a coating by evaporation to apply same in gaseouscondition to the workpiece.

The mentioned coating agents possess, above all, the effect that theyadhere well to the workpiece prior to impingement by the laser beam, andthis good adherence, however, after impingement by the laser beam, thatis to say, after changes by virtue of the thermal influences,disappears, so that the coating agent residues together with the ejectedmaterial can be easily removed chemically or mechanically.

Surprisingly, it has now been found that the mentioned coating agents,apart from the aforementioned effect of preventing the adherence of theejected material to the workpiece surface, enable attaining aconsiderable improvement of the quality of the hole or bore in the sensethat, on the one hand, instead of producing the conventional bores ofsubstantially cone-shaped configuration there can now be produced boresof cylindrical shape, and, on the other hand, there no longer occur thecrater-shaped locations which cannot be prevented with the techniquesknown up to the present. Additionally, there is the factor that also thedanger which exists when not using a coating agent that a bore or holewill again fuse together at its end, is practically eliminated by virtueof the inventive teachings. This additional effect is especially then ofdecisive importance when the bore hole should be used as a bearing for arotating journal or pin.

It has been assumed that these effects have been achieved in that Byvirtue of the small surface tension of the coating agent the ejectedliquid material droplets disperse upon the surface of the workpiece and,therefore, rapidly cool. As a result, the ejected material becomesbrittle and can be easily removed.

- By virtue of the accommodated index of refraction [1 n (coating agent)n (workpiece)], especially with rough surfaces which strongly dispersethe laser light, the surface quality of the workpiece is opticallyimproved.

The workpieces can consist of any optional material and can have anyrandom shape. A particularly interesting application of the inventivemethod is the forming of holes or bores in watch jewels or rubies. Inthis application, it is advantageous to add to the coating agent aquaternary ammonium-compound, for instance trimethyldecylammoniumchloride, in order to prevent the electric charging of the watch jewels.As a result, the jewels can be manipulated much better for processing orworking thereof.

Turning attention now to the apparatus structure depicted in the singleFIGURE of the drawing, it will be understood that such relates to anapparatus wherein the workpieces are watch jewels. This apparatus willbe seen to embody two band members 4 and which are guided overdeflecting rollers la, lb, 10, 1d and 2a, 2b, 2c, 2d, 2e, respectively,and a deflecting drum member 3. Of these two band members 4 and 5, oneof them, namely the band member 4 is formed of an adhesive material, forinstance rubber, and the other band member 5 of a smooth material, forinstance a soft-PVC. The deflecting rollers 1a, lb, 1c, Id and 2a, 2b,2c, 2d and 2e, respectively, are arranged in such'a manner that the bandmembers 4 and 5, respectively, are guided above one another along thepath 6 which extends from point 7 to point 8. Within this path there islocated the deflecting drum member 3, wherein both band members 4 and 5conjointly wrap around such deflecting drum member 3 through an angle ofapproximately as shown. The path 6 is in essence a transfer path wherebyworkpieces arriving from belt 5 are transferred to belt 4 and theworkpieces are inverted, as will be described in more detailhereinafter.

A first coating location or station in the form of a nozzle member 9 isarranged above the band member 5 in front, or upstream, of the path 6,whereas a second coating location or station in the form of a nozzlemember 10 is arranged behind, or downstream, this path 6. A fillingfunnel 11 as well as the feed vibrator l2, and finally, the infeedmagazine 13, are arranged in the direction of travel of the band 5 infront of the nozzle member 9, along an essentially horizontal path ofthe band member 5 between the deflecting roller 2a and the deflectingdrum member 3. A stripping device 14 is provided at the essentiallyvertical path of the band member 4 between the deflecting rollers 1a andlb, as shown.

The workpieces which are to be contacted at both sides with a suitablecoating agent are filled into the funnel 11 and through the action ofthe vibrator 12 are introduced into the infeed magazine 13, with thefront side or face of the workpieces facing towards the top. Theworkpieces are then delivered from the infeed magazine 13 onto thehorizontal path of the band 5 between the deflecting roller 2a and thenozzle 9 upon such band. With the front side or face of the workpieceslooking upwardly or towards the top, these workpieces are then passedbeneath the nozzle member 9 and at the same time coated or contacted bythe relevant coating agent. Thereafter, the thus treated workpiecesarrive at the location 7 where the band member 5 is placed over the bandmember 4 and together with such is wrapped around the drum member 3, asshown in the drawing. The workpieces are then retained between both ofthe band members 4 and 5 up to the location 8, where the smooth band 5by virtue of the deflecting roller 2e is again removed from the adhesiveband 4, to thus release the rear face or side of the workpiece which isnow situated towards the top, in other words looking in the direction ofthe nozzle member 10. In this position, the workpieces arrive at theoperating zone of the spray nozzle member 10, where now the rear side orface is appropriately coated. By means of the action of the deflectingroller la the workpieces now reach the stripping device 14, from wherethey are delivered to a suitable laser-beam device, which for thepurpose of preserving clarity in illustration has not been shown in thedrawing. The deflecting rollers lb and 2c form components of arespective non-illustrated cleaning device for each of both band members4 and 5, where the residues or remains of the coating material or agentcan be removed by any suitable removal means such as brushes from theband members 4, 5.

Continuing, an apparatus construction would be con ceivable in whichthere is dispensed with the common deflection of both band members 4 and5 and both of these band members would then only be guided above oneanother at a certain spacing along a predetermined path, this spacingbeing smaller than the height of the watch jewels. The watch jewelswould then be delivered to this path on the lower non-adhesive bandmember and after moving through the relevant path would adhere to theupper adhesive band member, so that the lower not yet coated face orside of the watch jewels is freely exposed and, in turn, can be coated.

Experiments have shown that in this manner it is possible in a simpleand a rational way to prevent the fixed adherence of the ejectedmaterial about the bores or holes produced by the action of thelaser-beams, and furthermore, to considerably improve the cylindricalityof such bores or holes.

While there is shown and described present preferred embodiments of theinvention, it is to be distinctly understood that the invention is notlimited to, but may be otherwise variously embodied and practiced withinthe scope of the following claims. Accordingly,

What is claimed is: 1. Apparatus for coating the major surfaces ofsubstantially disc-shaped workpieces comprising:

first and second band members positioned and arranged in partiallyoverlapping orientation defining a transfer path;

means for depositing substantially disc-shaped workpieces onto one ofsaid band members upstream of said transfer path;

first means positioned upstream of said transfer path for coating theexposed surfaces of said workpieces deposited onto said band member;

the spacing between said overlapping band members being of apredetermined height such that both band members are in simultaneouscontact with each workpiece passing through said transfer path;

said first and second band members including means for effectinginversion and transfer of said workpieces from said first band member tosaid second band member, said first band member transfer means being acontinuous element having a smooth, non-adhering surface, said secondband member transfer means being a continuous element having an adheringsurface for securely receiving said transferred workpiece; and

second means positioned downstream of said transfer path for coating thetransferred and inverted uncoated surface of said workpiece while saidwork-' pieces are retained on said adhering band surface.

2. The apparatus as defined in claim 1, further including a deflectingdrum member, and wherein said band members are conjointly trained withinsaid predetermined path, said superimposed band members both beingwrapped around said deflecting drum member and in cooperative contacttherewith through an arc of at least whereby workpieces are transferredfrom one band to the other.

3. The apparatus as defined in claim 1 wherein said band memberpossessing a smooth surface comprises polyvinyl chloride and said bandmember possessing a workpiece-adhering surface comprises a rubber-likematerial.

1. Apparatus for coating the major surfaces of substantially disc-shapedworkpieces comprising: first and second band members positioned andarranged in partially overlapping orientation defining a transfer path;means for depositing substantially disc-shaped workpieces onto one ofsaid band members upstream of said transfer path; first means positionedupstream of said transfer path for coating the exposed surfaces of saidworkpieces deposited onto said band member; the spacing between saidoverlapping band members being of a predetermined height such that bothband members are in simultaneous contact with each workpiece passingthrough said transfer path; said first and second band members includingmeans for effecting inversion and transfer of said workpieces from saidfirst band Member to said second band member, said first band membertransfer means being a continuous element having a smooth, nonadheringsurface, said second band member transfer means being a continuouselement having an adhering surface for securely receiving saidtransferred workpiece; and second means positioned downstream of saidtransfer path for coating the transferred and inverted uncoated surfaceof said workpiece while said workpieces are retained on said adheringband surface.
 2. The apparatus as defined in claim 1, further includinga deflecting drum member, and wherein said band members are conjointlytrained within said predetermined path, said superimposed band membersboth being wrapped around said deflecting drum member and in cooperativecontact therewith through an arc of at least 180* whereby workpieces aretransferred from one band to the other.
 3. The apparatus as defined inclaim 1 wherein said band member possessing a smooth surface comprisespolyvinyl chloride and said band member possessing a workpiece-adheringsurface comprises a rubber-like material.